Hydraulic synchronizer



1953 ZIMMERMAN HYDRAULIC SYNCHRONIZER Filed July 20, 1955 4 Sheets-Sheet1 FIG. I

INVENTOR: LOUIS ZIMMERMAN NOV. 11, 1958 zlMMERMAN 2,859,591

HYDRAULIC SYNCHRONIZER 4 Sheets-Sheet 2 Filed July 20, 1955 t o Smmnnuaunssaad INVENTORI LOUIS ZIMMERMAN NOV. 11, 1958 ZlMMERMAN 2,859,591

HYDRAULIC SYNCHRONIZER Filed July 20, 1955 4 Sheets-Sheet 5 FIG. 5

II VVEl VTOR. LOUIS ZIMMERMAN M rW- ATT'YS Nov. 11, 1958 LTZIMMERMAN2,859,591

HYDRAULIC SYNCHRONIZER Filed July 20, 1955 4 Sheets-Sheet 4 FIG?INVENTOR: LOUIS ZIMMERMAN 7M m gif zaf United States Patent 6 iHYDRAULIC SYNCHRONIZER Louis Zimmerman, Palos Heights, llli., assignorto U. S.

Industries, Inc., Chicago, 11]., a corporation of Delaware Thisinvention relates in general to a hydraulic synchronizer adapted for useon hydraulic metal working presses and more specifically the inventionrelates to a device for maintaining the slide of the press levelthroughout the entire stroke thereof.

In hydraulic presses slides are provided which reciprocate toward andaway from the press bed on which there is a die and a work piece to bestamped. The press is provided with a main hydraulic system whichprovides closing cylinders at each end of the press with hydraulic fluidunder pressure for moving the slide toward the bed. Pull-back cylindersare also provided to which hydraulic fluid under pressure is fed for thepurpose-of moving the slide away from the bed after the drawingoperation has been performed.

In hydraulic presses particularly, and especially the larger ones, thereis always a tendency for one end or the other of the slide to movefaster or slower than the other end especially during the workingstroke. Furthermore, if this is permitted to occur, there is apossibility that one part of the slide may press against a work piecewhen another part does not. There will, therefore, be a tendency forthat part of the slide which is out of contact with the work piece tocontinue to move, whereupon the slide becomes out of alignment andexerts undue pressures against the sides of the press frame. The presentinvention is designed to overcome these difficulties and to synchronizethe movements of the ends of the slide so that they will be maintainedat constant relative levels throughout the entire stroke of the slide.

It is, therefore, the principal object of the present invention toprovide, in a hydraulic metal working press, suitable mechanism forsynchronizing the reciprocating movement of a slide therein andmaintaining both ends of the slide at constant relative levelsthroughout the entire stroke thereof.

Another object of the invention is to provide, in a hydraulic metalworking press, a novel form of synchronizing valve operable in responseto movement of one end of the slide at a greater rate of speed than theother end thereof to cause said one end to reduce its speed, therebymaintaining both ends of the slide at constant relative levelsthroughout its entire stroke.

A further object is to provide a hydraulic synchronizer for a hydraulicmetal working press wherein a novel form of valve is located in a pilothydraulic circuit, and where in mechanical means actuate the valve tomaintain the slide level during the reciprocating movements thereof.

Still another object is to provide a hydraulic synchronizer for ahydraulic metal working press having a main hydraulic circuit forreciprocating the slide, and a pilot hydraulic circuit, wherein a novelform of valve is located in the pilot circuit and is actuated bymechanical means operated by the slide when one end of the slide movesfaster than the other end thereof, whereby the hydraulic pressure in themain circuit is reduced to retard the movement of said one end.

A still further object is to provide a hydraulic synchro- 2,859,591Patented Nov. 11, 1958 nizer for a hydraulic metal working press whereinrapid increases in speed of movement of one end of the slide thereinover the other end are prevented, and when conditions are such that suchincreases of speed tend to occur, and would occur except for the actionof the synchronizer, a novel form of valve will be actuated to overcomesuch tendency, whereby the slide is maintained level throughout itsentire stroke.

Other objects and advantages of the invention will become apparent uponreading the following description taken in conjunction with theaccompanying drawings, in which:

Fig. l is a diagrammatic illustration of a presse'mbodying the presentinvention;

Fig. 2 is a transverse sectional view through the diagrammaticillustration of the synchronizing valve of Fig. 1 taken substantiallyalong the plane of line 2-2 of Fig. 1;

Fig. 3 is a view similar to Fig. 2 taken along the plane of line 33 ofFig. 1;

Fig. 4 is a layout of the pilot hydraulic circuit in which thesynchronizing valve is located;

Fig. 5 is an elevational view, partly in section, of the synchronizingvalve;

Fig. 6 is a vertical transverse sectional view through the valve takenalong the plane of line 66 of Fig. 5, and

Fig. 7 is a vertical transverse sectional view through the valve takenalong the plane of line 77 of Fig. 5.

The hydraulic synchronizer of the present invention may be applied tohydraulic presses currently in use and thus has the advantage that thesystem need not be incorporated as an integral part of the press at thetime of its manufacture. The invention and its manner of operation maybe generally understood by a reference to Fig. 1 wherein the press bedis indicated by the numeral 1 and the slide is shown at 2.

Since conventional hydraulic presses utilize the closing and pull-backcylinders which are actuated hydraulically for reciprocating the slide,the details of such a hydraulic system are not illustrated herein. InFig. 1, however, the closing cylinders at each end of the press aredesignated by the numeral 3 and are shown as embodying a piston 4therein. A rod 5 connected to the piston 4 has the slide 2 suspendedtherefrom so that reciprocation of the piston 4 will also reciprocatethe slide 2.

In actual practice on a large press there will be two such closingcylinders at each end of the press and'two pull-back cylinders which areactuated to move the slide away from the bed. The main hydraulic circuitis shown only diagrammatically in Fig. 1 and is indicated at each end ofa press generally by the numeral 6. The hydraulic fluid is forcedthrough the circuit by means of a pump 7 at each end of the press drivenby a motor 8. The bydraulic fluid is pumped from a suitable source ofsupply through an inlet 9 and is forced outwardly under pressure throughpipes 10 connected to the cylinder 3. These cylinders are mounted on astationary part of the press frame so that when fluid is fed into thecylinder it will drive the pistons 4 downwardly carrying with them theslide 2 moving it toward the bed 1.

The synchronizer embodying the present invention utilizes a pilothydraulic circuit generally shown at 11, one for each end of the press.A control member 12 is associated with each pilot hydraulic circuit 11and includes a piston 13 and a cylinder 14. Hydraulic fluid underpressure from a suitable source (not shown) is forced through a pipe 15which communicates with the pipes 16 and 17 to direct fluid underpressure into the cylinder 14 at one side of the piston 13 therein.Apipe 18 also connects with the lead-in pipe 15 and communicates with aconduit 19 in communication with the cylinder 14 at the opposite side ofthe piston 13 therein. At

hydraulic fluid being delivered 91 end of the press in one of the pilothydraulic circuits, a conduit 2%) communicates with the conduits 18 and19 and connects with a pipe 21 which is also connected with an inletopening 22 inthe casing 23 of the synchronizing valve generallyindicated at 24.

The other pilot hydraulic circuit also has its conduit connected withthe conduits 18 and 19 but in this case the pipe Which leads to thesynchronizing valve is indicated by the numeral 21 and is connected toan inlet opening 25 in the casing 23 of the valve 24.

An outlet opening 26 also in the casing 23 has connected therewith apipe 27 which will carry hydraulic fluid back to the tank.

A valve 28 is located in each of the pipe sections 18 for the purpose ofregulating the pressure of the pilot to the synchronizing valve 24.

Each .of the control devices 12 is connected with its associated pump :7in'the main hydraulic circuit so that it may be Said that the controldevice is common to both the main hydraulic circuit and the pilothydraulic cirqllit- Pilot hydraulic pressure is directed against oneside of each piston 13 and is the same side connected to the pump 7which causes hydraulic pressure to be exerted through the main circuitto each of the closing cylinders 3. Pilot hydraulic fluidunder pressurepasses through each of the valves 28 and through each pipe 18 and isdirected through the pipes 19 to the outer end of each piston 13 inopposition to the pilot pressure at the opposite side thereof. Theregulated pilot pressure is also exerted through the conduits 21 and 21'to the synchronizing valve 24.

Thus far'it may be seen that when the pumps 7 are operating to directfluid under pressure either to the closing cylinders or to the pull-backcylinders, if anything should occur to cause either of the pistons 13 tomove outwardly toward the end of its associated cylinder 14, then thepressure in the associated main hydraulic circuit would be immediatelyreduced and the end of the slide being driven by that particularhydraulic circuit would immediately have its speed of movement reduceduntil the condition which caused the piston 13 to move outwardly wascorrected to return it to its nor mal position of equilibrium.

The construction of the synchronizing valve may be more clearlyunderstood by reference to Figs. 2 3, 5, and 7. With respect to Figs. 2and 5, it will be noted that the inlet 22 through the casing 23 leads toan annular recess 29 surrounding anouter tubular sleeve 30. This outersleeve 30 is provided with diametrically opposed openings 31 and 32extending therethrough. This Outer sleeve 30 surrounds an inner tubularsleeve 33 which is also provided with opposed openings 34 and 35 throughthe wall thereof. It'will be noted from viewing Fig. 2 and lookingtoward the right through the valve 24 as viewed in Fig. 1, that theopening 31 through the outer sleeve 30 is positioned immediately to theright of the opening 34 through the inner sleeve 33. These openings '31and 34 are normally out of communication with each other. Likewise, theopposite opening 32 through the wall of outer sleeve 30 is positioned tothe left of opening 35 through the inner sleeve 33 and these twoopenings normally are out of communication with each other.

Pilot fluid under pressure delivered through the inlet 22 will fill theannular recess 29 around the outer sleeve 30. Since the openings 31 and32 are in communication with the annular recess 29, these openings willalso be filled with the hydraulic fluid under pressure. If and when acondition occurs which will cause clockwise rotation of the outer sleeve30 as viewed in Fig. 2 or counterclockwise rotation of the inner sleeve33, then the open- 31 and 34 will immediately be brought intocommunication'with each other. At this time the openings 32 and 35 willalso be brought into communication, whereupon the pilot hydraulic fluidunder pressure being delivered through the inlet opening 22 will berelieved or reduced and the fluid will pass through to the interior 36of the inner sleeve 33. From this interior the fluid will then bedelivered through the outlet openings 37 in the wall of the sleeve 30 toan annular recess 38 in the casing 23 to the outlet passage 26 and pipe27 to be carried back to the tank. The reason that the pressure of thepilot hydraulic fluid will be relieved is because the valve 28 in pipe18 is set so that suflicient fluid will be unable to pass therethroughto satisfy the pressure requirement. This fluid pressure then iscompensated for by the fluid passing through pipes 16 and 17 to theinner side of piston 13 which will cause the piston to move outwardly.This in turn reduces the pressure in the main hydraulic circuit so thatless pressure will be exerted upon the particular piston'which isdriving that end of the slide.

As will presently be seen, the reduction of pressure in the mainhydraulic circuit at one end of the slide will slow down the movement ofthat end of the slide immediately causing relative rotation between theinner and outer sleeves in the opposite direction to again position theopenings 31 and 34 and the openings 32 and 35 out of communication witheach other. At this moment the required pressure is satisfied by thepilot fluid passing through valve 28 and pipes 18, 20 and 21 causing thepiston 13 to resume its normal position and increasing the pressure atthat end of the slide exerted by the main hydraulic circuit.

Referring now to Fig. 3 and viewing the section through thesynchronizing valve as looking toward the right thereof from theposition shown in Fig. 1, it will be noted that the outer sleeve 30 issurrounded by a second annular recess 39 in communication with the inletpassage 24 connected to the pipe 21' associated with the pilot hydrauliccircuit at the opposite end of the slide. In this area the outer sleeve30 is provided with the opposed openings 40 and 41 through the wallthereof. The inner sleeve 33 has the opposed openings 42 and 43 throughthe wall thereof. The openings 40 and 42 are normally out ofcommunication with each other and the openings 41 and 43 are likewiseout of communication under normal conditions. However, when conditionsare such as to rotate the outer sleeve 30 in a counter-clockwisedirection or the inner sleeve 33 in a clockwise direction, therespective openings 40 and 42 and the openings 41 and 43 will be broughtinto communication with each other permitting the flow of the hydraulicfluid from pipe 21 through the annular recess 39 and the communicatingpassages in the walls of the outer and inner sleeves to the interior 36of the inner sleeve where it is carried away in the same mannerpreviously described through the outlet opening 26 back to the tank.

Since the pilot fluid passing through the valve 28 at this particularend of the slide cannot be supplied fast enough to satisfy the pressurerequirements, it will result in outward movement of piston 13 whichcauses a reduction in the fluid pressure of the main hydraulic circuitassociated with this end of the slide, thereby retarding the movement ofthat end of the slide. Again, as will presently be seen, this conditionwill cause the respective openings 40 and 42 and the openings 41 and 43to be positioned out of communication with each other, whereupon thepilot pressure will increase to move the piston 13 inwardly and returnthe operation of the main hydraulic circuit back to normal.

The arrangement of the elements embodying the invention is such thatwhen the right-hand end of the slide as viewed in Fig. 1 movesdownwardly at a greater rate of speed than the opposite end thereof, theinner sleeve 33 will move relative to the outer sleeve 30 in acounterclockwise direction, as viewed in Fig. 2. If, however,

the left-hand end of the slide moves at a greater rate of speed than theright-hand end thereof, the outer sleeve 30 will move relative to theinner sleeve 33 in a counterclockwise direction as viewed in Fig. 3.

To accomplish this result the outer end of the inner sleeve 33 isconnected with a shaft 44 on which is mounted a pinion 45 in mesh with arack 46mounted on the right-hand end of the slide 2. The outer sleeve 30has secured thereto a similar shaft 47 on which is mounted a pinion 48in mesh with a rack 49 secured to the opposite end of the slide. Thus,as the slide moves downwardly carrying with it the racks 46 and 49, arotation of the pinions 45 and 48 will occur causing alike rotation ofshafts 44 and 47 and the inner and outer sleeves 33 and 30,respectively, connected therewith. Thus, during the downward movement ofthe slide, both the inner and outer sleeves will rotate together in thesame direction and presumably at the same rate of speed which willprevent any communication between the openings through the walls ofthese sleeves. If, however, the right-hand end of the slide begins tomove at a greater rate of speed than the left-hand end thereof as viewedin Fig. 1, then pinion 45 will rotate faster than pinion 48 and innersleeve 33 will likewise rotate faster than outer sleeve 30. Since bothsleeves are rotating in a counter-clockwise direction as viewed in Fig.2, it will be immediately apparent that as soon as the inner sleeve 33rotates faster than the outer sleeve 30, communication will beestablished between the openings 31 and 34 and the openings 32 and 35.When this occurs, the pilot pressure of the fluid being delivered to thevalve through pipe 21 will be reduced, thereupon reducing the pressureof the hydraulic fluid in the main circuit associated with theright-hand end of the slide, thereby immediately causing the speed ofmovement of that end of the slide to be retarded in the manner aboveexplained. As soon as this retarding movement takes place, the pinion 45will rotate at a slower rate to bring it into conformity with the speedof rotation of the pinion 48.

If the left-hand end of the slide is caused to move at a greater rate ofspeed than the opposite end thereof, then the outer sleeve 30 willrotate at a greater rate of speed than the inner sleeve 33, whereuponcommunication will be established between the openings 40 and .42 andthe openings 41 and 43 causing a drop in pres- ;sure in the line 21' asabove explained, and a corresponding drop in pressure of the mainhydraulic circuit asso- .ciated with the left-hand end of the slide,thereby retarding its reciprocating movement and bringing the speed ofrotation of the pinion 48 into conformity with the rotation of pinion45.

Fig. 4 illustrates the actual layout of the pilot hydraulic circuitshown diagrammatically in Fig. 1. The same reference numerals refer tothe same parts in both figures. In the actual layout, however, the pipes21 and 21 are not connected directly to the synchronizing valve 24 butare connected indirectly thereto through a solenoid operated 4-way valvegenerally indicated at 50. The diagrammatic showing of Fig. l issatisfactory for the purpose of illustrating the principle of operationof the invention. However, it is obvious that on the return or upperstroke of the slide 2 the outer and inner sleeves 30 and 33 will rotatein a direction opposite to that which occurred during the downwardmovement of the slide. Thus, the synchronizing valve would not operateduring upward movement of the slide without reversing the connections tothe valve of the pipes 21 and 21'. In other words, the valve wouldoperate to maintain the slide level only when the inner and outersleeves thereof rotate in a counter-clockwise direction as viewed inFigs. 2 and 3. When the slide moves upwardly, these sleeves will rotatein a clockwise direction so that in order for the valve to functionproperly the pilot hydraulic circuit at the left of Fig. 1 must bebrought into operation when the inner sleeve 33 rotates too fast becauseof the increased '6 speed of movement at the right end of the slide, asviewed in Fig. 1. Conversely, the pilot hydraulic circuit at the rightof Fig. 1 must function when the outer sleeve 30 rotates faster than theinner sleeve due to the increased speed of movement of the left end ofthe slide, as viewed in Fig. 1.

Summarizing briefly, during the down stroke of the slide, the fluid frompipe 21 should be delivered to the inlet opening 22 in the valve and thefluid from pipe 21' should be delivered to the inlet opening 25 in thevalve. On the up' stroke of the slide, the fluid from pipe 21 should bedelivered to inlet opening 25 and the fluid from pipe 21' must bedelivered to the inlet opening 22.

The solenoid operated 4-way valve 50 shown in Fig. 4 accomplishes theforegoing result. This valve is commercially available and is well knownin the art and its operation need not be described in detail. It issuflicient for present purposes to indicate in Fig. 4 that the pipe 21leads to the valve 50 and for the down stroke of the slide the fluid isdirected through the valve and outwardly through the pipe 51 to theinlet opening 22 of the valve 24. Pipe 21' from the other pilothydraulic circuit leads also to the valve 50 and during the down strokeof the slide the fluid therefrom will pass through the valve and throughthe conduit 52 to the inlet opening 25 in the valve 24.

When the slide reaches its lowermost position it is customary and wellknown construction to have the slide operate a limit switch whichoperates suitable valves in the main hydraulic circuit to direct thefluid from the closing cylinders to the pull-back cylinders, whereuponthe slide is then moved upwardly away from the bed. At this same momentthe limit switch will also actuate the solenoid of valve 50 so thatduring the upward movement of the slide fluid in pipe 21' will bedelivered through the valve 50 and outwardly through the conduit 51 tothe inlet 22. Likewise, the pilot fluid from pipe 21 is changed so thatit will flow through the valve 50 and outwardly through conduit 52 tothe inlet 25. When the slide reaches its uppermost position anotherlimit switch will be actuated to reverse the flow of the pilot hydraulicfluid and to again change the main hydraulic fluid back to the closingcylinders.

During the up stroke of the slide the synchronizing valve will operatein the same manner as on the down stroke of the slide to synchronize themovement of the ends of the slide to maintain them substantially equalin their speed of movement. When one end of the slide moves faster thanthe other, then the inner and outer sleeves will be rotated relative toeach other, thereby reducing the pressure against the outer end of oneof the pistons 13 allowing the piston to move outwardly and causing adrop in pressure in the main hydraulic circuit to retard the movement ofthat particular end of the slide.

Another feature of the invention is the provision of mechanism which hasa damping effect on the rate at which one end of the slide will increaseits speed over the other end thereof. That is to say, in the absence ofsuch a device one end of the slide might have a tendency to eitherrapidly increase its speed or move a relatively great degree over theother end of the slide, which would thereupon have a tendency to movethe pistons 13 back and forth constantly. This self-centering orequalizing feature is illustrated in greater detail in Figs. 5 and 6 ofthe drawings. I

In Fig. 5 particularly it will be noted that the inner sleeve 33 extendsoutwardly. beyond the casing 23 of the valve 24 and is provided with thestepped annular shoulders 53 and 54. A ring 55 is placed over theshoulder 53 and issecured to the inner sleeve 33 by suitable means, suchas a key 56. The ring 55 is then held in place by a suitable retainingmeans including a ring 57 adapted to fit over the shoulder 54.

The outer sleeve 30 also extends outwardly beyond the end of the casing23: of the valve 24 and at its outer end is spaced from the shoulders 53and 54 on the inner sleeve An outer ring 58 then fits over the outersleeve 30 and abuts against the end 59 of the casing 23. This outer ring58 is also rotatably secured to the outer sleeve 30 by means such as thekey 60. This outer ring is then held in place by suitable meansincluding a retaining ring 61.

' The outer ring 58 is provided with a plurality of spaced radiallyextending openings 62 each of which receives a bushing 63. An arm 64 islocated within each bushing 63 and is mounted therein for longitudinalreciprocation. The inner end of each arm 64 has rotatably mountedthereon a roller 65 which is positioned normally at the bottom of arecess 66 in the ring 55. This arrangement may be more clearlyunderstood by viewing Fig. 6.

The outer end of each arm 64 is provided with an extension 67 of lesserdiameter, each of which is received in a Suitable recess in a ringsegment 68. There is provided one such ring segment 68 for each arm 64.

The segments 68 are placed cireumferentially around the ring 58 and eachis adapted to, seat in a recess on the periphery of the ring 58 providedby the shoulders 69 and 70. A set screw 71 extends laterally inwardlythrough each segment 68 and has the inner tapered end thereof receivedin a hole 72 through the extension 67, thereby to prevent the roller arm64v from rotating about its longitudinal axis.

Each segment 68 is provided with grooves 73 and 74 around the outerperiphery thereof so that when all of the segments are in place end toend around the ring 58, these grooves 73 and 74 will be continuous andannular. Extension springs 75 and 76 are located in the annular grooves73 and 74, respectively, for the purpose of holding the roller arms 64normally inwardly and tending to maintain the roller 65 of each such armin the innermost point of the associated depressions 66.

Thus, the ring 55 in which the depressions 66 are located is keyed tothe inner sleeve 33 and rotates therewith. The arms 64 are positioned inthe ring 58 which in turn is keyed to the outer sleeve 30. When theinner sleeve 33 rotates relative to the outer sleeve 30, it must moveagainst the force of the springs 75 and 76 holding the arms 64 inwardly,and will tend to force the rollers 65 to climb upwardly along the slopeof the depressions 66. Likewise, relative movement of the outer sleeve30 will urge the arms 64 outwardly against the force of the springs75am! 76.

This equalizing device has a tendency to keep the inner and outersleeves rotating at, a constant rate. If. however, either end oftheslide begins to move more rapidly than the otherend. and at a ratesufiicient to move one of the sleeves relative to the other against theforce of the springs 75 ,and 76, then the valve will be actuated aspreviously described to retard the speed of that particular end of theslide, thus synchronizing the end movements thereof and tending tomaintain them constant and to retain the slide level throughout itsentire stroke.

It has been determined in actual practice that when the slide startsdownwardly from its upper position, there is a tendency for the slide torock but with the use of this equalizing mechanism in the valve itself,the tendency to rock becomes less as the slidernoves downwardly so thatby the time the draw takes place, there will be little or no movement ofthe pistons 13 except for that which may be caused by unequal pressuresexerted by each end of the slide after it contacts the work piece.

Changes may be made in the form, construction and arrangement of partsfrom those disclosedherein without in any way departing from the spiritof the invention or sacrificing any of the attendant advantages thereof,provided, however, that such changes fall within the scope of the claimsappended hereto.

The invention is hereby claimed as follows:

1 A hydraulic synchronizer adapted for use with a hydraulic metalworking press having a reciprocating slide,

comprising a plurality of pilot hydraulic circuits, synchronizing valvemeans common to said circuit, a like plurality of main hydrauliccircuits for reciprocating the slide, means to actuate said valvemeanswhen one end of the slide moves at a greater rate of speed than theother end thereof, and control means, common to each of said main andpilot circuits operable when said valve means is actuated to control thepressure in the main circuit to which it is connected and retard thespeed of movement of said one end of the slide.

2. A hydraulic synchronizer adapted for use with a hydraulic metalworking press having a reciprocating slide, comprising a plurality ofpilot hydraulic circuits, synchronizing valve means common to saidcircuits, a like plurality of main hydraulic circuits for reciprocatingthe mechanical means connecting the ends of the. slide with said valvemeans and operable to actuate said valve means when one end of theslide, moves at a greater rate of speed than the other end thereof, andcontrol means common to each of said main and pilot hydraulic circuitsoperable when said valve means is actuated to control the pressure inthe main hydraulic circuit to which it is connected and retard the speedof movement of said one end of the slide.

3. A hydraulic synchronizer adapted for use with a hydraulic metalWorking press having a reciprocating slide, comprising a plurality ofpilot hydraulic circuits, synchronizing valve means common to saidcircuits including outer and inner tubular sleeves having passagesthrough the walls thereof, said passages being normally out ofcommunication with each other but adapted to communicate with each otherupon a relative rotation between said sleeves, a like plurality of mainhydraulic circuits for reciprocating the slide, means to actuate saidvalve means by rotating one of said sleeves with respect to the othersaid sleeve when one end of the slide moves at a greater rate of speedthan the other end thereof, and control means common to each of saidmain and pilot hydraulic circuits, said valve means being operable whenactuated to relieve the pressure on one side of one of said controlmeans, whereby the pressure on the opposite side thereof will act onsaid control means to reduce the pressure in the main circuit at saidone end of the slide and retard the speed of movement thereof.

4. A hydraulic synchronizer adapted for use with a hydraulic metalworking press having a reciprocating slide, comprising a plurality ofpilot hydraulic circuits, synchronizing valve means common to saidcircuits, a like plurality of main hydraulic circuits for reciprocatingthe slide, a rack at each end of the slide and reciprocaoie therewith, apinion in mesh with each of said racks, a shaft for each of said pinionsconnected directly with said valve means and operable to actuate saidvalve meanswhen one end of the slide moves at a greater rate of speedthan the other end thereof, and control means common to each of saidmain and pilot hydraulic circuits operable when said valve means isactuated to control the pressure in the main hydraulic circuit to whichit is connected and retard the speed of movement of said one end of theslide.

5. A hydraulic synchronizer adapted for use with a hydraulic metalworking press having a reciprocating slide, comprising a plurality ofpilot hydraulic circuits, synchronizing valve means common to saidcircuits including outer and inner tubular sleeves having passagesthrough the walls thereof, said passages being normally out ofcommunication with each other but adapted to communicate with each otherupon a relative rotation between said sleeves, a like plurality of mainhydraulic circuits for reciprocating the slide, a rack at each end ofthe slide and reciprocable therewith, a pinion in mesh with each of saidracks, a shaft for eachof said'pinijons, one shaft being connected withsaid outer sleeve and the other shaft being connected to said innersleeve, whereby when one end of the slide moves at a greater rate ofspeed than the other end thereof one of said sleeves will rotate withrespect to the other sleeve to actuate said valve means, and controlmeans common to each of said main and pilot hydraulic circuits, saidvalve means being operable when actuated to relieve the pressure on oneside of one of said control means, whereby the pressure on the oppositeside thereof will act on said control means to reduce the pressure inthe main circuit at said one end of the slide and retard the speed ofmovement thereof.

6. A hydraulic synchronizer adapted for use with a hydraulic metalworking press having a reciprocating slide, comprising a plurality ofpilot hydraulic circuits, synchronizing valve means common to saidcircuits, a like plurality of main hydraulic circuits for reciprocatingthe slide, a rack at each end of the slide and reciprocable therewith, apinion in mesh with each of said racks, a shaft for each of said pinionsconnected directly with said valve means and operable to actuate saidvalve means when one end of the slide moves at a greater rate of speedthan the other end thereof, and control means including a piston andcylinder assembly common to each of said main and pilot hydrauliccircuits operable when said valve means is actuated to control thepressure in the main hydraulic circuit to which it is connected andretard the speed of movement of said one end of the slide.

7. A hydraulic synchronizer adapted for use with a hydraulic metalworking press having a reciprocating slide, comprising a plurality ofpilot hydraulic circuits, synchronizing value means common to saidcircuits including outer and inner tubular sleeves having passagesthrough the walls thereof, said passages being normally out ofcommunication with each other but adapted to communicate with each otherupon a relative rotation between said sleeves, a like plurality of mainhydraulic circuits for reciprocating the slide, means to actuate saidvalve means by rotating one of said sleeves with respect to the othersaid sleeve when one end of the slide moves at a greater rate of speedthan the other end thereof, and control means including a piston andcylinder assembly common to each of said main and pilot hydrauliccircuits, said valve means being operable when actuated to relieve thepressure on one side of one of said control means, whereby the pressureon the opposite side thereof will act on said control means to reducethe pressure in the main circuit at said one end of the slide and retardthe speed of movement thereof.

8. A hydraulic synchronizer adapted for use with a hydraulic metalworking press having a reciprocating slide, comprising a plurality ofpilot hydraulic circuits, synchronizing valve means common to saidcircuit including outer and inner tubular sleeves having passages of theslide and reciprocable therewith, a pinion in mesh with each of saidracks, a shaft for each of said pinions, one shaft being connected withsaid outer sleeve and the other shaft being connected to said innersleeve, whereby when one end of the slide moves at a greater rate ofspeed than the other end thereof one of said sleeves will rotate withrespect to the other sleeve to actuate said valve means, and controlmeans including a piston and cylinder assembly common to each of saidmain and pilot hydraulic circuits, said valve means being operable whenactuated to relieve the pressure on one side of one of said controlmeans, whereby the pressure on the opposite side hereof will act on saidcontrol means to reduce the pressure in the main circuit at said one endof the slide and retard the speed of movement thereof.

9. A hydraulic synchronizer adapted for use with a hydraulic metalworking press having a reciprocating slide, comprising a plurality ofpilot hydraulic circuits, synchronizing valve means common to saidcircuits, at like plurality of main hydraulic circuits for reciprocatingthe slide, means to actuate said valve means when one end of the slide'moves at a greater rate of speed than the other end thereof, equalizingmeans operably connected with said valve actuating means to prevent anyrapid increase in the speed of movement of one end of the slide over theother end thereof, and control means common to each of said main andpilot circuits operable when said valve means is actuated to control thepressure in the main hydraulic circuit to which it is connected andretard the speed of movement of said one end of the slide. v

10. A hydraulic synchronizer adapted for use with a hydraulic metalworking press having a reciprocating slide, comprising a plurality ofpilot hydraulic circuits, synchronizing valve means common to saidcircuits, a like plurality of main hydraulic circuits for reciprocatingthe slide, mechanical means connecting the ends of the slide with saidvalve means and operable to actuate said valve means when one end of theslide moves at a greater rate of speed than the other end thereof,equalizing means connected between said mechanical means and said valvemeans to prevent any rapid increase in the speed of movement of one endof the slide over the other end thereof, and control means common toeach of said main and pilot circuits operable when said valve means isactuated to control the pressure in the main hydraulic circuit to whichit is connected and retard the speed of movement of said one end of theslide.

References Cited in the file of this patent UNITED STATES PATENTS1,900,050 Ernst Mar. 7, 1933 2,312,213 Ferris Feb. 23, 1943 2,380,973Kopp Aug. 7, 1945

